Successful iMac Upgrade to GTX 880M

Mein Problem

My daughter has a 2011 27” iMac (base model) and it just cannot keep up with modern games. XCOM 2 for example was unplayable even at the lowest settings. I decided to try an upgrade to a GTX 880M and used this guide as baseline even tough it was for the 21.5” model.

The GTX 880M was purchased off of eBay and reportedly came from an Alienware Laptop.

Meine Reparatur

The upgrade went great! The 880M is longer than the 6770M but still fits, especially because we also replaced the HD with a SSD. The difference in playing games is amazing, most games auto-detected the new card and changed their settings to the highest settings. XCOM 2 runs perfectly at medium settings, which is comparable to my 2015 5K iMac.

This upgrade was hard, but really worth it!

Mein Rat

To get the computer to boot the first time I needed to use Safe Mode by holding down the shift key as soon as I hear the start up chime.

Once booted into safe mode, installing the nvidia Web Drivers made the system work perfectly. I also installed the CUDA drivers, but thats not required.

Yes, I used the card with the original firmware. No, the display is stuck at full brightness but that's not an issue for me so I haven't messed with it. System is still running great, now on macOS Sierra.

This fix works perfectly for osx sierra, but no longer works for high sierra. Any suggestions on getting this up and running on the new OS? I checked and verified csrutil was disabled before I ran the setup, I think apple really wants us to buy new machines now.. Would so be great if anybody has a fix!